Pot^-to flfp ":■--■■'-' tle-e '^n eggplants n?.;/ "be held in chi^ck vrith a duat 
c->::tpii'ir.,;; 0.75 p--rcpnt of rotenorie. — Cr-oslj:-', Chupp, p.nd Lr-i"b- (^S) in I939. 
Th- r.-=nnc,.7lv^.nis A.:ricnltiiral E>— erinent Station (^1^) in 19;^q re- 
"ort'^-c. th^t flea '!:'-^tle in.ivir:" to to-cacco and potatoes is causi-d 'b;'" the 
potato flea, oertle earlr in the Reason. The greatest ■nrnti'-cti'~n a^rainst 
oee.tle dr-Tiage to tobacco lea'^^es was afforr.f^d oy dtxstins -^-fith a fixture of l 
''.p.rt of .^rroimd cuhe root C^ n'Orcs^nt , -^f rotenone) and "^ p^rts of Rterili^r-'d 
toDF.cc- dust (xilt-r dust r^r^ria "..nin^: after nicotin" extr~cti'^n) vrith 1 -^^rt 
to goo '^•f a vrettin^- a.^cnt , Ultrrwet. The rnat-Tial vras pppli^^d at thr r.-^te 
of " to R pounds pr-r acre to neyly_ set 'olpnts^ increpsing to 10 to 15 pounds 
nor '^cre after topping. 
Enitrir n-'^rvula (E.), the tobacco flea cc-etle 
Cha.ml)-rlin (_^) in 1'^^"^ r '--''' or ti^-d that, of various dusts test-d aeriinst 
thr tohacco flep. heotle, derri'= dust -produced thp hir.'h'-st -lortalit." x^dthin 
th- sh-^rtest t-eriod of tine, D?rris cp.us.od an imnediate and extreme irrita- 
tion, as evivdenced "by the insect's con\''ulsi'"e effort f ollo^-finrv application 
of the rn^tcrial. 
The sp-me author (69) reported in 19?*^ p-'^'^- also in a t:''r>ewritten 
report t'^' the Division of -Trr.ch Crop and G-arden Insects, of the Bureau, 
in 1935, ^'^^^ pt Q,uincy, Ela, , coth dcrris and cu'be diluted t^ p rotonone 
c'ntent of 1 percent "by adjnixture vrith tobacco dust or kaolin g»ve .?ood 
control of the tobacco flea "beetle on tohaoco in tobsacco-plant teds. The 
infestation was li.rht . Feith'-r poison injured the foliage e-^en vrhen applied 
undilut'^d, Derris and cuhe dusts containing 0,75 nercent of rot-^none rid 
nevrly set fi^ld tohj'.cco of overvintered flea hretles. Field teats on matur- 
ing tohacco indicated that a dust containing 0.75 percent of rotenone, ap- 
plied at the rate of S to 10 pounds per acre, is effective in controlling 
flea b'^etles vrhen the infestation is light-. As diluents for derris '^^r cuhe 
the follovring vrere tried: Georgia clay, talc, celit'--, and a tohacco dust 
cO worcent of which passed through a. 150-mpph screen. The last is the most 
s''^itatle for shade- totacco dusting. Derris ap'oli'^d at the rate of S r-ounds 
oer acre killed 9^.8 percent of th^ flea beetles and cuhe applied at the 
rate of 7.5 pounds per acre killed S3. 2 percent. Both powders contained 0.75 
percent -^f rot.en'^ne, 
Stanle.- and Marcovitch ( 35^ ) i'^- 1935 reported tha.t derris-r-^ot dust 
containing 0.75 percent of rotenone vras found to ret n^iickly on flea beetles, 
hut ?ft-r the second dry beetles appeared ag?in r-n olpnts, ev--: though dT- 
ris w s still '^n th^ leo-'-es. To determine hovr long derris retains its toxic- 
ity vrhen ex'oosed t'^^ climatic, conditi-ns, an .-experiment was performed as 
follovrw: Si-o.ll leaves vrere removed from t'^b^cco, placed in vials vrith water, 
and dusted heavily vrith derris dust containing 0.75 P'^'rcent of rotenone. 
They vrere then flaced in o.irect s\inlight. Ecich evening. at 5 o'clock the 
leaves wore rem.ovod to the insectpry for ■•■-rotection from rain, and at 7 ^..m* 
they vrere again rjlpcod outside. Each da" for 5 days -> dusted leaf vras re- 
rinvrci. p,nd pl-'-ced in a. cage vith fie? beetles, r.nd the kill noted. It vras 
found that derris lost its toxicity rapidly upon exposure, giving 100-per- 
tont kill the first c'^y, 55 percent the second, and 20 percent the third. 
Data are shown in the follovrin«: t'ble: 
